PWM cooling fan(s) control using ECM

[dhutton]

Originally Posted by parsonsj

Another (related) question: does anybody have a line on the voltage vs pressure map of the GM AC refrigerant sensor (AC Delco pn 15-51258)? I've been in contact with a vendor about a standalone fan controller for AC and engine coolant temp.

I've done some googling without much luck, though why I would expect anything other than bad luck is a good question.

I think the sensor map would be resistance in ohms versus pressure. I am guessing this is something you could measure with a little ingenuity, a tank of MIG gas, a regulator and an ohmmeter.

Don

[parsonsj]

Sensor data, just pulled from the car:

[parsonsj]

Originally Posted by Don

I think the sensor map would be resistance in ohms versus pressure

It's a 3 wire sensor: 5V, ground, signal. So the ECU is measuring voltage. Internally, the mechanism is resistance, but that is translated to voltage for convenience.

[dhutton]

Thanks for explaining it. I was puzzled a little. Pretty clever measuring it in the car.

Don

[parsonsj]

Originally Posted by Don

Pretty clever measuring it in the car.

Glad I'm rehabilitating my reputation after the cardboard in the intercooler fiasco.